Clutch drum

ABSTRACT

A clutch drum includes a cylindrical drum body having a spline portion consisting of plural extruded angles and extruded channels formed by pressing, and plural pressed-out portions formed at the spline portion, one side wall of the pressed-out portions having a continuous shape without any rupture, the other side wall of the pressed-out portions being formed by half blanking of the clutch drum body so as to stop a snap ring threat.

This is a division, of application serial No. 06/502,757, filed June 9,1983 and now U.S. Pat. No. 4,813,522.

BACKGROUND OF THE INVENTION

This invention relates to a clutch drum.

FIG. 1 shows a conventional frictional clutch for use in an automatictransmission. A press-formed clutch drum 1 has a spline portion 1a. Asnap ring groove 1b is formed in each extruded angles of the splineportion 1a. A snap ring 2 is set in the snap ring grooves 1b so thatplural clutch plates 3 can be prevented from moving in an axialdirection as well-known.

FIGS. 2 through 4 show in detail such snap ring grooves in aconventional clutch drum. A snap rig groove 13 is formed in eachextruded angle or inward protruding portion 12 in a clutch drum 11.

The snap ring grooves 13 are formed by the following steps: Two parallelcutting lines are formed in a predetermined portion of each extrudedangle 12 where the snap ring groove 13 is to be formed. The distancebetween the two cutting lines is slightly longer than the width of thesnap ring 14. The portion of the extruded angles 12 between the cuttinglines is pressed out so as to form the grooves 13. The reference 15designates such pressed-out portions. A recess resulting from thepressing-out constitutes the snap ring groove 13.

In the above-mentioned conventional clutch drum, however, thepressed-out portions 15 are partly cut off from the body of the clutchdrum 11 along the cutting lines so as to be weak.

For such a reason, a thick steel plate must be used in order to avoidthe rupture of the pressed-out portions 15 defining the snap ringgrooves 13. In addition, a large size of special machine for carryingout the steps of forming two cutting lines and pressing out the clutchdrum must be used. Also, for the same reason, it takes a long productiontime.

SUMMARY OF THE INVENTION

The object of this invention is to provide a clutch drum in which aclutch drum body can be strengthened.

According to this invention, there is provided a clutch drum including acylindrical drum body having a spline portion consisting of pluralextruded angles and extruded channels formed by pressing, and pluralpressed-out portions formed at the spline portion, one side wall of thepressed-out portions having a continuous shape without any rupture, theother side wall of the pressed-out portions being formed by halfblanking of the clutch drum body so as to stop a snap ring thereat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing a portion of a conventionalautomatic transmission equipped with a prior art clutch drum;

FIG. 2 is a schematic perspective view showing a part of a conventionalclutch drum;

FIG. 3 is a plan view showing in an assembled condition the clutch drumshown in FIG. 2;

FIG. 4 is a sectional view showing the clutch drum of FIG. 3;

FIG. 5 is a schematic perspective view showing only an essential portionof a clutch drum according to a first embodiment of this invention in andisassembled condition;

FIG. 6 is a plan view showing the clutch drum of FIG. 5 in an assembledcondition;

FIG. 7 is a sectional view showing the clutch drum shown in FIG. 5;

FIG. 8 is a schematic perspective view showing a clutch drum accordingto a second embodiment of this invention; and

FIG. 9 is a schematic perspective view showing a clutch drum accordingto a third embodiment of this invention, in a disassembled condition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 5, 6 and 7 show a first embodiment of this invention. A clutchdrum 21 has a plurality of inward protruding portions or extruded angles22 a trapezoid-like shape in section. A snap ring groove or channel 23is formed in each extruded angle 22 by pressing out a portion of eachextruded angle 22. One side wall 23a of the snap ring groove 23 has acontinuous bulging shape so that the clutch drum 21 is not cut offthereat. As best shown in FIG. 7, the other side wall 23b is partlyruptured by half blanking of a predetermined portion of the clutch drum21. A snap ring 24 contacts the side wall 23b when the snap ring 24 isassembled in the clutch drum 21.

The reference 23c denotes an extruded angle or pressed-out portion whichconstitutes the bottom portion of the snap ring groove 23.

The clutch drum 21 is remarkably strengthened at the grooves 23 becausethe pressed-out portion 23c can function as a rib so as to increase thestrength of the extruded angle 22.

The snap ring grooves 23 of the clutch drum 21 can be pressed by asimple moving in the radius direction of a punching die (not shown).Therefore, the productivity is high. If desired, the snap ring grooves23 can be formed by a general purpose press machine.

FIG. 8 shows a second embodiment of this invention. The extruded angles32 of the clutch drum 31 are pressed out inwardly as designated by 33.Such pressed-out portions 33 project inwardly to form stops. One sidewall of the pressed-out portions 33 is continuous and does not have anyrupture. The other wall of the pressed-out portions 33 is formed by halfblanking of the extruded angles 32 so as to allow support of the snapring 34. In this embodiment, the snap ring 34 can move only in onedirection (downwardly in FIG. 8).

When the pressed-out portions 33 are formed, a punching die can bearranged outside the clutch drum 41. Therefore, a small size of clutchdrum can be made.

FIG. 9 shows a third embodiment of this invention in which an outer sideportion of a clutch drum 41 is used as a spline portion. In thisembodiment, extruded channels 42 are used to stop the snap ring 44outside the clutch drum 41.

In this embodiment, the extruded channels 42 are pressed out by bulgingand half blanking thereof thereby to form pressed-out portions 43 whichstop the snap ring 44.

What is claimed is:
 1. A clutch drum comprising a generally cylindricaldrum body having spline means formed by a plurality of radially inwardprotruding portions and radially outward protruding portions withrespect to a center axis of the drum body, said radially inward andoutward protruding portions extending in parallel to said axis and beingarranged alternately around the drum body, said drum body having aplurality of pressed-out portions arranged circumferentially along thedrum body on the spline means and each of said pressed-out portionsbeing displaced radially with respect to said center axis to form firstand second side walls, said pressed-out portions adjoining unpressedportions of the spline means, said first side wall being substantiallyperpendicular to said axis and extending circumferentially along thedrum body, said first side wall being partly ruptured from a firstadjoining unpressed portion of the spline means and being partly in onepiece with said first adjoining unpressed portion of the spline means,said first side wall being so displaced radially with respect to saidcenter axis as to partly overlap with said first adjoining unpressedportion and to define an abutment for a snap ring, said abutment definedby a non-overlapped portion of said first side wall adjoining saidoverlapped portion of the first side wall, and said second side wallopposite the first side wall in a direction parallel to said center axisand being continuous with a second adjoining unpressed portion of thespline means without any rupture between said second side wall and saidsecond adjoining unpressed portion.
 2. A clutch drum as set forth inclaim 1, wherein each pressed-out portion is formed at each of theradially inward protruding portions and displaced radially inward withrespect to the center axis of the drum body thereby to form a snap ringstop inside the clutch drum body.
 3. A clutch drum as set forth in claim1, wherein each pressed-out portion is formed at each of the radiallyoutward protruding portions and displaced radially outward with respectto the center axis of the drum body thereby to form a snap ring stopoutside the clutch drum body.
 4. For a clutch drum including a generallycylindrical drum body, said drum body having a spline means formed by aplurality of radially inward protruding portions and radially outwardprotruding portions with respect to a center axis of the drum body, saidradially inward and outward protruding portions extending in parallel tosaid center axis and being arranged alternately around the drum body,said drum body having a plurality of pressed-out portions arrangedcircumferentially along the drum on the spline means to define stoppingmeans for a snap ring, a method of forming each of said pressed-outportions comprising the steps of:displacing a first predeterminedportion of the spline means radially with respect to said center axisalong a first line extending circumferentially of the drum body so as toform a first wall which is continuous with a first adjoining undeformedportion of the spline means without any rupture between said first walland said first adjoining undeformed portion; and displacing a secondpredetermined portion of the spline means in the same direction as thatof the displacement of said first portion along a second line which isparallel to and spaced from said first line a predetermined distance inthe direction along said center axis so as to form a second wall, saidsecond portion being displaced in such a manner that said second wall ispartly ruptured from a second adjoining undeformed portion of the splinemeans and partly in one piece with said second adjoining undeformedportion and that said second wall is partly overlapped with said secondadjoining undeformed portion.
 5. For a clutch drum including a generallycylindrical drum body having spline means formed by a plurality ofradially inward protruding portions and radially outward protrudingportions with respect to a center axis of the drum body, said radiallyinward and outward protruding portions extending in parallel to saidcenter axis and being arranged alternately around the drum body, saiddrum body having a plurality of pressed-out portions arrangedcircumferentially along the drum body on the spline means to definestopping means for a snap ring, a method of forming each of saidpressed-out portions comprising the steps of:pressing-out a firstpredetermined portion of the spline means radially with respect to saidcenter axis along a first line extending circumferentially of the drumbody so as to form a first wall which is continuous with a firstadjoining undeformed portion of the spline means without any rupturebetween said first wall and said first adjoining undeformed portion; andblanking a second predetermined portion of the spline means in the samedirection as that of the displacement of said first portion along asecond line which is parallel to and spaced from said first line apredetermined distance in the direction along said center axis so as toform a second wall which is opposite said first wall, said secondportion being blanked in such a manner that said second wall is partlyruptured from a second adjoining undeformed portion of the spline meansand partly in one piece with said second adjoining undeformed portionand that said second wall is partly overlapped with said secondadjoining undeformed portion.